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What you really need to know about house paint and painting.

Clear, comfortable weather makes September the ideal month to paint. And this particular September, paint is very much in the news. Formulations are changing, as oil-base paint is being singled out as a significant air polluter. As the box on page 86 describes, the way many Westerners approach painting will be different.

A glance at paint's history

For centuries, paint was essentially lead. Ancient Egyptians, Greeks, and Romans made a sort of paint by treating lead with wine or vinegar. Later painters mixed up white-lead paste, then added linseed oil, turpentine, a drier, and colored pigments in oil. Such paint had great hiding power, was easy to work with, stuck where it was applied, and weathered well.

Unfortunately, it also poisoned people, by skin absorption, respiration, or ingestion (the paint chips tasted sweet). Today, paint with more than .06 percent lead by volume is banned in the U.S.

There's also been a shift away from oil as the base for paint. It began during World War II, when linseed oil and the solvents that cut it were scarce. By the mid-'5Os, synthetic replacements were outperforming natural ingredients. Today, practically all paints consist of some form of synthetic resins or polymers.

Modern solvent-thinned paints still work like the old oil-base paints, only more effectively; alkyds (a hybrid word designating the combination of alcohols and acids that produces the synthetic resins) have replaced most or all of the natural oils. Alkyd formulations are comparatively low in cost and have excellent color retention, durability, and flexibility.

But the most dramatic shift has been away from solvent-thinned paints in favor of water-thinned ones. Today, latex is the consumer standard, accounting for nearly 80 percent of the paint sold.

What's in paint? Three components

Pigment gives paint its color and hiding power (see page 82).

Vehicle is the combination of synthetic resins and oils that surrounds the pigment particles. It determines cohesiveness (providing the strength for the dried paint film) as well as adhesiveness.

Carrier (often listed as the volatile vehicle) thins the syrupy resins so the paint will flow on; it evaporates first as the paint dries, and it allows for varying consistencies thicker or thinner. Water is the carrier for latex paints, petroleum distillates for alkyd paints.

The cost of these raw materials can be 30 to 60 percent of the price of paint. A good paint has high-quality components in proper proportion to each other; you really do get what you pay for.

Some paints contain pigments extended with silica, talc, or gypsum from highly refined minerals to just clay. Sometimes ground so fine that they'll stay in permanent suspension, these extenders behave as thickeners. Used correctly, they can cut gloss or improve flow. Used simply as a cost-saving measure by the manufacturer, they reduce hiding power and durability.

Alkyd is now the main resin in solvent thinned paint. Several different resins- acrylic, polyester, vinyl, and blends- are used in latex paints. In general, high resin content is the mark of durable, abrasion resistant, impact-resistant, flexible paint. Usually, the higher the resin content, the higher the gloss, but paints can be listed as high-resin "scrubbable" flats.

Are today's paints better?

Experts disagree. The quality range is much wider, but the best are better and the worst much worse. Paint life span is impossible to predict; there are too many factors specific to your situation. Be wary of guarantees.

In judging a brand, see if the paint levels itself out, showing few brush or roller marks, ripples, or pockmarks. It shouldn't run or sag on the wall during application-the sign of a thin paint (or perhaps you're applying too thick a coat).

The paint should hide what's underneath it (page 82). It should dry hard, to resist denting, scratching, marring. Hardness correlates with resin content and gloss. Old-timers might swear by linseed oilbase paint, but tests at the USDA's Forest Products Laboratory suggest that today's best choice for routine outdoor home use is an acrylic latex with a resin content of at least 20 percent.

Gloss: what you get is what you see

Resin makes paint durable, easy to clean, and moisture resistant; the more resin, the higher the gloss. High-gloss paint reflects light, emphasizing defects in walls and ceilings as well as showing off whatever it coats. (Textured paints and flats break up light; that's why they're used on large walls and ceilings, particularly if those surfaces are uneven or damaged.

On labels, gloss goes by various names: luster, shine, sheen. Paint can be termed high-gloss, semigloss, or flat (mat). Semigloss can be called eggshell, velvet, satin, or pearl, and can range from nearly flat to very shiny, depending on the manufacturer. There's no industry standard.

With enamels, the pigments used should be top quality, with little filler.

Latex glosses may stay tacky much longer than you think. They may feel dry to the touch, but don't stack things on the newly

painted surface too soon, or they may bond to it. Cure can take two weeks to a month.

Latex: easy to work with, clean up

Once a name for synthetic rubber, latex is now synonymous with water-thinned paint. The pigment-holding resin particles are held in suspension. Instead of absorbing oxygen to form a hard coating, the particles actually coalesce into a tight film that is insoluble in water when dry.

Latex is easy to work with. It can be applied to damp surfaces. It doesn't require a wet edge; you can stop midwall, start later, and never see where you left off. It dries fast, though a full cure can take up to four weeks. Best of all, you can clean up wet paint with soap and water.

You can tell latex quality by the type of resin used: acrylic is best, vinyl acrylic and other blends next, all vinyl not as good. All are flexible (particularly the acrylics), stretching and shrinking with the wood or whatever they're painted on. On the down side, you can't sand latex especially gloss latex to a desirable texture; it will tear off or melt to a gummy consistency. Latex enamel doesn't level as well as alkyd enamel and won't hold as high a gloss but a top-quality latex product will hold its gloss better and longer than its alkyd counterpart, especially in areas exposed to weather.

Alkyds: higher gloss, harder surface Alkyd paint (often called oil-base paint) doesn't dry like latex; oxygen absorbed from the air changes the molecular structure of the solids, so you can sand an alkyd surface- a critical factor if you're using successive coats to provide high glosses. The paint will also hang on a little harder, because the solvent will carry the paint into the substrate more than water would. On old, poorly prepped surfaces, like chalking walls, choose an alkyd.

It will also hold a higher gloss, and the paint film is more moisture resistant.

On the minus side, alkyds are harder to apply, aren't as sag resistant as latex, are harder to touch up, and require cleanup with mineral spirits.

Polyurethanes are similar to alkyds. Best used indoors, they're available in clear or solid colors (avoid semitransparent formulations), and they dry very hard.

What about stains and clear finishes?

Exterior stain is actually thin paint with little pigment. Latex stains don't penetrate as do alkyd ones, so they offer less protection on raw wood.

Stains, preservatives, and water repellents are better than paint for rough or weathered wood siding.

Bleaching stain gives the look of uniform, naturally weathered wood. It's a mix of a water repellent, bleach, and gray pigment, formulated to speed weathering and wear off as natural bleaching takes over.

Transparent exterior coatings have their own clarity working against them. The sun penetrates the coating and degrades the wood under the finish. Ultraviolet rays tend to turn the finish brittle; it will crack and peel as the wood shrinks and swells underneath it. To prevent major problems, the new coating must go on before the old one starts to deteriorate.

Now that you know, how do you buy?

First, indoors, consider the likely duty. Light-duty surfaces won't need washing, because there's little moisture, grease, or dirt in the air, as in living rooms and bedrooms; a cheaper paint may suffice. Moderate-duty surfaces may need an occasional cleaning: children's rooms, halls. Heavy-duty surfaces in kitchens and bathrooms will be exposed to moisture, grease, and plenty of traffic; use quality paint for these.

The label should tell you what the paint works well for and on, about how much it will cover per gallon, what kind of surface preparation is necessary, what the appropriate primer is, and any precautions. Unless you know better, follow the directions on the paint can explicitly.

Several Eastern states now require a composition list on the label; if you get a can in the West that spells out how much and what types of pigment and resin are in the can, it's probably a national brand.

If you aren't sure what you need, stop by two or three paint stores and compare what the salespeople tell you. With luck, you'll find a well-versed salesperson who has used many products. You may even be able to negotiate a price break on quantity. Bargains at discount houses are rarely bargains, unless you know exactly what you're buying.

"Know who you're buying from because it's going to get even harder to really know what you're buying," one manufacturer warned us. It doesn't pay to scrimp, by buying either an inferior or an inappropriate coating.

Almost all complaints about the product involve cheap paint or poor prep. As one retailer told us: "The cheaper the paint, the more critical the prep, but there comes a time when all the prep in the world can't overcome cheap paint.

" Preparation: get that surface clean!

Make sure the surface is free of dirt, oil, grease, rust, and paint flakes. You may need to scrape and sand to achieve this, or use a scrub brush and detergent, but you can usually let water under pressure do a lot of the work.

Except on board-and-batten siding, where water could be blown through the walls, a pressure sprayer (available at tool rental yards and some paint stores) will take many walls down to a clean, tight surface. The pressure-sprayed water will also clean off water-soluble microscopic crystals that are usually deposited on walls and eaves by sea air or smog. These crystals have finally been pinpointed as the culprit for a lot of peeling paint.

You don't have to take walls down to a bare subsurface, only to sound, tightly adhering paint. Sand the edges around undamaged paint, then spot-prime all bare wood.

Plan to paint right away (but make sure wood is dry). For new or newly cleaned surfaces, even a few days' exposure will decrease paintability and paint lifespan.

Paint is not a preservative: it will not prevent decay if conditions are favorable for fungal growth. To clean mildew off walls of an average-size house, scrub them with a mix of 3 ounces TSP (trisodium phosphate), 1 ounce dry detergent, 1 quart chlorine bleach, and 3 quarts water.

Clean already-painted glossy surfaces, knocking off the gloss to give the surface "tooth" to hold the new paint; use fine sandpaper, TSP solution, or liquid sanding preparation (good for hard-to-sand areas or for removing floor wax from baseboards). Don't use a household spray cleaner for this job; the oil it contains to make the surface shine prevents paint from sticking. Wash greasy surfaces thoroughly with a TSP solution.

Periodic cleaning can reduce the need for frequent repainting; an annual cleaning with water and a mild detergent will prolong the life of most paints, inside and out.

Nailing, caulking, filling

Use hot-dipped (galvanized) nails for exterior repairs; other types can bleed rust through the top coat.

Caulk all cracks and gaps between walls and eaves or trim where moisture might enter. Indoors, seal cracks between cabinets, trim, woodwork, and walls. Make sure the caulk formulation you choose is paintable (check the label) and let caulk set according to product label.

Fill deep holes in stages, giving each layer time to dry. Remove any hardware.

Priming-easy road to a good finish

Primer makes your top coat both adhere and look better. Always use a primer on bare or deteriorated surfaces, or if you're changing paint type or making a drastic color change.

If in doubt about what you're painting over, use an alkyd or oil primer; latex primer can lift old oil-base paint.

Alkyd primers and latex finish coats adhere well to each other. Plan to paint the top coat within 14 days of priming, or soapy primer components can bleed to the surface and disrupt the bond.

If you're priming to block stains, use quick-dry alkyd or shellac-base primer, brushed or sprayed on. Use shellac sparingly it can lead to early paint failure at the point of application.

Water repellents are good stabilizers for raw wood before priming and painting. Treat new wood windows, sash, and trim before painting, but make sure you pick a repellent that's paintable. Allow two warm, dry days before painting.

Right tools make the job easier

If you've taken the trouble to prepare the surface correctly, you'll certainly want to put the paint on well. Pictured on page 80 is the basic array of professional tools ones that effectively apply the paint the easiest way possible.

A good brush is a joy to use. It's well balanced, it holds a lot of paint, and it will put the paint where you want it. Look for multiple lengths of split (flagged) bristles packed tightly through a 3/4- to 1 -inch thickness for a standard 4-inch brush. Test any brush for springiness, little fanning, and no bristle gaps. A reputable dealer will put the right brush in your hand for the job you need to do.

Don't use a natural bristle brush in latex; like a beard, the bristles go limp in water. Polyester brushes stay stiff in water, humidity, and heat, keeping their shape for detail work. Nylon is more abrasion resistant but can lose stiffness on hot days.

Skip roller shields for your roller; they're more trouble than without. "Anyway, spatter is caused by excessive speed," one contractor told us. Roller covers come in natural or synthetic materials. Once again, synthetics are better for latex paints; your dealer will suggest the correct nap length for your job. Roll from a grid on a 5-gallon bucket. Your job will go more quickly and easily with less mess.

Sprayers? They're great for deeply textured, hard-to-reach, or multipiece surfaces with many nooks and crannies, like eaves, lattices, or very rough stucco. They require careful masking and dropcloth placement. Be careful: the nozzle pressure is great enough to inject the paint into your skin (if that happens, get immediate medical attention).

Tips from the pros

Here are pointers, culled from talks with professional painters. Ceilings. First decide how you'll reach everything. Begin in a dark corner and paint toward the light. Brush around edges and light fixtures (remove ceiling plate if possible). Carry less paint on your brush or roller when working overhead.

Paint across short dimension of your ceiling. Roll a big, comfortable W, then fill it in. Don't lift the roller for the first few strokes. Stay light on finish strokes.

Doors. Roll doors with a lint-free cover, then brush out the paint in the direction of the grain. Match the latch edge to the room it opens into, the hinge edge to the room it opens away from.

Enamel. Brush on generously, with a light touch; avoid overbrushing (causes bumpy surface). Work fast; don't try to touch up.

Insects. If they get trapped on new paint, let it dry before brushing them off.

Outside. Do main surfaces first, then overhangs, then trim.

Paint in fair (above 50 degrees), dry weather cooler temperatures mean poor adherence. To avoid wrinkling, fading, or loss of gloss in solvent-thinned paints and streaking of latex paints, apply after morning dew dries and stop at least 2 hours before evening damp. Heavy dew on a still-setting surface can create serious problems or even finish failure.

Avoid painting in direct sun; if you can, try to follow the sun around the house. Don't apply solvent-thinned paints to cool surfaces that will be heated by sun in a few hours, or they can blister.

Taping. Remove masking tape while the paint is still slightly wet so the paint on the work won't bond to the paint on the tape. Don't leave tape on windows in the sun; it will bond to the glass.

Timing. For best adherence, try to apply all coats within two weeks of each other.

Walls. "Cut in" (paint the edge) around ceiling and baseboards. Use a wide brush; it acts as its own guide, letting you paint a straight line with no squiggles. Then roll in W sections, starting at the top. Roll each new section toward the last wet edge from about 2 feet away.

Keep plenty of paint on your roller: "the purpose of painting is to apply paint.

Windows. Use a tapered sash brush, lightly loaded, on frames. Let paint slightly overlap the glass; wipe off excess with rag wrapped around putty knife blade. With practice, you can avoid masking.

Keep a clean brush on hand for dusting trim just before you paint.

Smog, the EPA, and cans of paint yanked off the shelf

Abruptly in July, with no coverage in newspapers or on television, paint retailers in California began yanking some brands of solvent-thinned nonflats off their shelves.

In fact, by the time this magazine reaches you, hundreds of paint stores in California may be virtually without gallon cans of quality solvent-thinned enamels. Contractors in many areas will be unable to buy such paint in quantity. Some California paint manufacturers may even have closed up shop.

What's happened? In brief, the federal Environmental Protection Agency lost patience. Solvents used in paints, stains, lacquers, sealers, and the like contain organic compounds that evaporate and become building blocks for smog. (For example, every day in the Southern California air-quality district, an estimated 60 tons of emissions from paint and similar products flavor the air; mobile sources-cars, trucks - produce 400 tons-55 percent of the total.)

In 1977, states set up plans to clean up their air as part of the federal Clean Air Act. In key smog-prone counties, technology-forcing standards were set to markedly reduce paints' solvent content. Manufacturers met the first reduction step (from 450 to 380 grams per liter of volatile organic compounds) in 1979 by increasing the ratio of solids pigments, resins, and so forth- to solvents. The resulting paint was usually thicker, slower drying, and less durable. The lowered solvent content adversely affected flow and the paint's self-leveling capability.

The final drop to 250 grams per liter in 1981 couldn't be formulated with a product that performed up to any reasonable consumer expectation. Exemptions were requested and granted on a regular basis as manufacturers attempted to find a compliant product that still "worked."

Now the EPA is refusing to acknowledge any more exemptions. In July 1987, manufacturers n California were ordered to stop making paints exceeding the 1981 limits. And distributors and retailers in California urban areas were told to stop selling such paints as of September 1. After January 1, 1988, it may be illegal for you to apply such products from anything larger than a quart can. Fines, likely levied against manufacturers, retailers, and contractors but theoretically applicable to everyone, can run up to $25,000 a day per violation.

The standards have drastically reduced the availability of high-quality solvent-thinned enamels in many counties. But the same paints sold in quarts are exempt for now, pending further EPA study. The results, present and anticipated:

-If you have a choice on what coating to use, opt for a water-thinned product, as it's the only one you can be sure will remain on the market.

-If you don't have a choice-and there are situations where only a solvent-thinned coating will suffice-hope the quarts stay on the market.

-Read this story; the issues it raises are now more critical for an acceptable paint job.

-Don't be surprised to see large paint stores springing up on the interstates west of Reno and Las Vegas.

-For the time being, solvent-thinned primers the bridge from solvent-thinned topcoats to water-thinned (latex) topcoats will remain on the market.

-Anticipate lawsuits to be in the news on this matter as other categories of coatings are affected.

-If oil-base products meeting the current EPA standards do reach the market, expect them to be notably inferior to those you're used to.

Ironically, they may require recoating about twice as often --further adding to atmospheric pollution.

What gives paint its hiding power? Its brightness? Color?

What color of paint hides best? Usually, white or earth-tone pastels- because pure white pigment is the main component that gives paint its hiding ability. Titanium dioxide (TiO2), the premier choice for almost all paints, solvent-thinned and latex, has long since supplanted poisonous white lead. In any mix, TiO2 provides hiding, durability, and brightness.

Cheap white paints usually aren't very white; they use fillers and toners costing a 10th the price of TiO2. Certain fillers, such as microfine silica, may sustain hiding power, but they'll sacrifice pure, clear color. Some kinds of TiO2 will chalk slowly; so-called "self-cleaning" paint with this pigment lets wind and rain carry away surface dirt and soot. But chalk can stain,so don't use such paint above materials you want to stay unmarked.

Nonchalking TiO2, used in almost all gloss paints, often has zinc oxide added as a mildewcide.

TiO2 has two main drawbacks; it's expensive and it doesn't absorb colorants well. Various tint bases-white, pastel, midtone, dark done-usually have increasingly less TiO2. In high-quality white or pastel, it might be 2 1/2 pounds per gallon; for a midcolor base, 2 pounds; for a dark base, less than 1 pound.

Some earth-tone colorant (unber, brown oxide, lampblack) will improve hiding power. These colorants will continue to sustain hiding power into dark browns, blues, and grays. But in many cases, when you tint paint very dark you sacrifice hidability.

"To get some colors, you have to drown the TiO2 in pigment," a chemist told us. Most orange, pink, and red pigments are nearly transparent; to produce strong colors, your sacrifice much of the paint's hiding ability.

With a properly prepared and primed wall, a dark color may be no problem, although its finish may not be too durable. Don't expect one-coat coverage with any paint over most color changes.

But when mixing any color, stick to the color system of the paint manufacturer you choose. Each system is based on compatibility of the pigments with it; some don't react well with others, and that can cause premature film failure.
COPYRIGHT 1987 Sunset Publishing Corp.
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Title Annotation:includes related articles on quality of paints
Date:Sep 1, 1987
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